Bellows valve

ABSTRACT

The present invention relates to a device which can be used in an off-shore or onshore oil and/or gas well for the purpose of increasing the production of the well. The device comprises an outer structure in which a first and a second pressure-actuated bellows device are arranged, the first and second pressure-actuated bellows device, via a support means, being in fluid communication with each other. The support means is fixedly mounted internally in the outer structure, the support means thereby delimiting an open and a closed space for respectively the first and the second pressure-actuated bellows device, wherein the closed space is filled with a fluid under pressure, whilst the open space is in fluid communication with a surrounding fluid.

The present invention relates to a device that is used in connectionwith equipment, various types of work and operations carried out inconnection with oil and/or gas wells onshore and offshore, and moreparticularly the present invention relates to a pressure-controlleddevice that is operated within a given pressure range.

Hydrocarbons, such as oil, gas and/or mixtures thereof, are normallyfound in accumulations under pressure in porous formations in a bedrock.These natural hydrocarbon reservoirs are exploited by drilling one ormore boreholes into the bedrock. When these boreholes have been fullydrilled and the well is in production, various processing installationsthat are located on or above the seabed will be able to process thehydrocarbons fully or partially.

However, there are hydrocarbon reservoirs where the natural flow ofhydrocarbons to the surface is not sufficient to allow or maintainprofitable production of the well. This may, for example, be due to theviscosity and/or weight of the hydrocarbons, or that the pressure in theoil well is too low to counter the hydrostatic pressure of the fluid inthe well as well as the counter-pressure that the processinginstallations on the surface exert on the fluid in the oil and/or gaswell.

The hydrocarbon reservoir may also, after being in production for sometime, “lose” the pressure that is necessary to drive the hydrocarbonsout of the reservoir, which will not make it profitable to operate thewell any longer.

For such hydrocarbon reservoirs a number of systems and variousprinciples have therefore been developed which are able to increase theproduction of the well with the aid of so-called artificial lifting. Thetwo most common systems used today are water injection and gasinjection. During gas injection gas is injected at high pressure intothe annular space between the casing and the production tubing. As arule, pressure-controlled valves, so-called injection or gas liftvalves, are used to be able to supply and control or manage the amountof gas that flows into the actual production tubing.

Such gas lift valves may also be used during a start-up phase of a well,where completion fluid is found in both the well annulus and theproduction tubing. To start production in such a well, completion fluidthat is in the annulus firstly must be displaced therefrom, through oneor more gas lift valves, and up to the surface through the productiontubing.

Similarly, a gas lift valve may, for example, be used after a well forvarious reasons has been shut down, with the result that a fluid fillsat least parts of the annulus in the well, or that gas from a productionfluid migrates to the surface, which may lead to the pressure in thewell becoming too low to allow production therein to be resumed withoutthe well being supplied with external pressure support, for example,pressure support by gas injection.

How these pressure-controlled valves are configured and arranged in thewell will depend on a number of parameters. For example, according tothe size (diameter) of the production tubing and the injection pressureavailable, so-called gas injection points will be provided at one ormore locations in and along the production tubing, the specificconfiguration for each individual well thus being adapted for optimalgas injection. The pressure-operated valves, such as a gas lift valve,will then be installed at these gas injection points, at the same ordifferent locations along the longitudinal direction of the productiontubing with the purpose of being able to initiate gas injection, suchthat through this artificial “lifting” an optimal production of the wellis obtained.

The gas lift valve(s) may then be operated or controlled according to anumber of different principles, for example, by means of pressure, wherethere are pressure differences around and/or across the valve thateffect the control of the valve(s), i.e., the opening and closingthereof.

One of the objects of the present invention is therefore to provide adevice which is operated and/or controlled by pressure differences.

Another object of the present invention will be to provide a device thatcan be connected to an injection device and thus be used together withthe injection device to operate and/or control the injection of a fluidinto an oil and/or gas well.

Yet another object of the present invention will be to provide a devicethat operates within a predetermined pressure range.

These objects are attained by means of a device as disclosed in thefollowing independent claim, with additional features of the inventionset forth in the dependent claims and the description below.

A device according to the present invention is specifically intended tobe used in connection with a start-up phase in an oil and/or gas well,in which well the whole or parts of the well annulus and productiontubing are filled with, for example, a completion fluid. Before theproduction of the well can start up, the completion fluid that is in theannulus and/or production tubing must be displaced and replaced by aninjection fluid, for example, a gas. Gas or nitrogen under highpressure, in a suitable manner, will then be pumped into the wellannulus (the space between the well casing and the production tubing).

An optimal positioning of the various injection valves in such a well isidentified using simulation tools for each individual well, the optimalconfiguration varying from well to well, depending on the specificparameters of the well. A different composition of well fluid duringstart-up will, moreover, mean that there is a need to have severallevels of injection points in the well. However, when optimal productionof the well has been achieved, there will only be a need for a(stimulation) injection point, this being located as far down in thereservoir as possible.

One or more pressure-operated valves, comprising the device according tothe present invention, which are arranged in the longitudinal directionof the production tubing, will then, in the light of the simulation thathas been conducted, be so-called “start-up units”, where these units areto be closed successively downwards in the well after the well hasstarted up its production, so that the injection fluid is distributeddownwards to the desired “start-up unit”.

When the pressure above such a “start-up unit” is great enough, it isopened and a throughflow of completion fluid through the unit isallowed, such that the completion fluid can flow from the annulus intothe production tubing. The introduction of additional pressurised gasinto the annulus will result in the completion fluid being displacedfrom the annulus and up through the production tubing. This process isrepeated for each injection point downwards in the well. When thepressurised gas begins to flow into the production tubing, the well canstart production from unit to unit until the main injection point isreached. It is then only this injection point that is in use. All theother initial units are closed.

The device according to the present invention can also conceivably beused when the well does not have sufficient pressure to drive thehydrocarbons up to the surface, or during a start-up of a well which hasbeen temporarily shut down, where a fluid has filled up at least partsof the annulus and/or the production tubing, or where the productionfluid has remained for some time in the annulus and/or the productiontubing and where gas has migrated to the surface, the result being thatpressure in the well is too low for the well to begin producing withoutreceiving pressure support from gas injection.

It should be understood, however, that the device according to thepresent invention may also have other areas of use, for example, inconnection with equipment that is used in an oil and/or gas well,equipment that is at the top of the process or that is located on theseabed.

The present invention relates to a device that comprises an outerstructure. A bore is formed in the outer structure, which bore isdelimited by an end surface that is arranged at one end of the outerstructure. Thus, the outer structure will be closed at one of endthereof and open at an opposite end. One or more through holes areprovided in an area close to the open end of the outer structure, whichallows a fluid surrounding the device to flow into the device. Thetermination or edge of the outer structure may furthermore be configuredwith connecting means so as to allow the device to be coupled orconnected to other equipment or tools, for example, a gas lift valve.

The outer structure of the device may be made in a single piece, or itmay be composed of several substructures.

According to the present invention, a first and a secondpressure-actuated bellows device are arranged in the longitudinal boreof the outer structure. Such a pressure-actuated bellows device, whenseen in section in its longitudinal direction, may have a shape that maybe oval, polygonal, curved, but preferably not circular, in order toobtain a simple compression or extension of the bellows device. Thiscompression or extension is obtained by subjecting the pressure-actuatedbellows device(s) to pressure conditions and/or reciprocal actuation.

The pressure-actuated bellows device may, for example, be made of aplurality of sections or lamellae which, when assembled, form thebellows device. It is also conceivable that the bellows device can bemade by machining, moulding etc. Furthermore, the pressure-actuatedbellows devices may be made of a metallic material, but they may also bemade of a non-metallic material or of an elastomeric material. In somecases the pressure-actuated bellows devices may also be made ofdifferent materials.

The pressure-actuated bellows devices are further made hollow and theyare delimited at one end by a flange or the like, whilst at their otherend (open end) they are connected to a support means. How thisconnection is made and the structure of the connecting means isexplained below.

The pressure-actuated bellows devices may further be designed to holdthe same or different fluid volumes. This will mean that one of thepressure-actuated bellows devices will act on the secondpressure-actuated bellows device in such a way that the secondpressure-actuated bellows device is compressed/extended by the same ordifferent length as the first pressure-actuated bellows device, that the“force” which is transmitted by the first and the secondpressure-actuated bellows device is the same or different etc.

The foregoing means that the pressure-actuated bellows devices and thesupport means form a closed unit, which unit preferably is filled withan incompressible fluid.

When arranged in the outer structure, the first pressure-actuatedbellows device will only be supported by the support means, whilst thesecond pressure-actuated bellows device will be supported by the supportmeans at one end and a piston rod at the opposite end.

As the first and the second pressure-actuated bellows device arearranged in the longitudinal bore in the outer structure, thepressure-actuated bellows devices must have a radial extent (diameter)that is smaller than the radial extent (diameter) of the longitudinalbore, when seen in the longitudinal direction of the bore.

According to a preferred embodiment of the present invention, both theouter structure and the pressure-actuated bellows devices are configuredwith a circular cross-section, but they may have any suitable shape.

The first and the second pressure-actuated bellows device are furtherhydraulically connected to one another via the support means, whichmeans that the pressure-actuated bellows devices will act mutually onone another in their axial direction. If, for example, the firstpressure-actuated bellows device is actuated such that it is compressed,the compression will be “transmitted” via the support means so that thesecond pressure-actuated bellows device is extended a certain length.Similarly, actuation of the second pressure-actuated bellows device willresult in the first pressure-actuated bellows device being extended orcompressed, depending upon whether the first pressure-actuated devicewas compressed or extended. The incompressible fluid will then be“transmitted” from the one pressure-actuated bellows device to theother, this “transmission” between the pressure-actuated bellows devicesthus being able to operate and control the opening and closing of thedevice.

The support means is suitably fixedly mounted internally in the outerstructure. This may be done, for example, by welding, adhesive bonding,screwing etc. As the support means has a radial extent (diameter) thatessentially corresponds to the radial extent (diameter) of the bore, thesupport means, the outer structure and the closed end of the outerstructure will define a fluid-tight space, in which fluid-tight spacethe first pressure-actuated bellows device is arranged. The secondpressure-actuated bellows device will then be arranged in the space thatis defined by the support means, the outer structure and the open end ofthe outer structure.

The support means, according to a preferred embodiment of the invention,is configured as a hollow, closed cylinder, where in the top and bottomface of the closed cylinder, seen in the longitudinal direction of thecylinder, there is provided a through hole or opening. The first and thesecond pressure-actuated bellows device are then connected through theiropen end to the holes in the top and bottom face of the support means,such that the first and the second pressure-actuated bellows devicetogether with the support means form a closed unit.

In a preferred embodiment of the invention, the cavity that is definedby the first pressure-actuated bellows device, the support means and thesecond pressure-actuated bellows device is preferably filled with anincompressible fluid.

According to one embodiment of the invention, a “floating” piston may beprovided in the support means, the piston being allowed to move in theaxial direction of the support means when one or both of thepressure-actuated bellows devices are subjected to an external force.The piston has a radial extent (diameter) which is essentially the sameradial extent as the inner surface of the support means. When the pistoncomes into contact with the top or bottom face of the support means, thepiston will not move further, thereby also stopping the movement of thepressure-actuated bellows devices.

In another embodiment of the present invention, a delay device may beprovided in the support means, this delay device having the purpose ofdelaying the flow of the incompressible fluid into the closed unit. Inits simplest form, this delay device may comprise a plate that isconfigured with one or more through holes. The plate is suitablyfastened internally in the support means.

Since through the invention it is desired to provide a device whichoperates within a predefined pressure range, the pressure-actuatedbellows devices are supported internally in the longitudinal housingbore in such a way that the support means per se forms a limitation (endstop) for the movement that respectively the first and the secondpressure-actuated bellows device are permitted to make. This means thatif the first pressure-actuated bellows device is subjected to pressurewhich results in it being compressed in its axial direction, the supportmeans, i.e., the end stop, will prevent a further extension of thesecond pressure-actuated bellows device. Similarly, the secondpressure-actuated bellows device, when the pressure surrounding itincreases, will only be allowed a certain displacement in its axialdirection before its movement is stopped by the end stop, whereby alsothe first pressure-actuated bellows device is prevented from beingfurther extended.

In an alternative embodiment, the end stop may be a sleeve which ispreferably arranged on the inside of the support means, the sleeve thenextending outwards from the support means and some length into the axialdirection of the pressure-actuated bellows device. The end stop may bearranged in each of the pressure-actuated bellows devices, or only inone of them. However, it should be understood that the sleeve can alsobe arranged on the outside of the pressure-actuated bellows device, andin that case the sleeve can be connected to the support means.

The end stop may also be constituted of a flange or the like that isarranged internally in the outer structure.

In a preferred embodiment of the present invention one or both of thepressure-actuated bellows devices may be so configured that when adesired compression of the pressure-actuated bellows device hasobtained, the pressure-actuated bellows device will essentially becompressed so that a further compression thereof is not obtainable. Thismeans that the pressure-actuated bellows device in its maximumcompressed position will act as a solid, rigid element, which gives thepressure-actuated bellows device substantial mechanical strength andresistance to pressure.

By introducing a fluid into the fluid-tight space in which the firstpressure-actuated bellows device is located, i.e., the fluid-tight spacedefined by the outer structure, the support means and the closed end ofthe outer structure, and subsequently pressurizing it with a specificpressure, which results in the first pressure-actuated bellows devicebeing subjected to a preset pressure, the first pressure-actuatedbellows device will be actuated by the preset pressure and compressedagainst the support means. The first pressure-actuated bellows devicewill then be fully compressed, i.e., that it assumes the position of asolid rigid element, which cannot be compressed further. Thiscompression of the first pressure-actuated bellows device will thenresult in the second pressure-actuated bellows device being extended alength, with the effect that the second pressure-actuated bellowsdevice, which via a piston rod or the like is connected to a valve body,will force the valve body into contact with a valve seat, which resultsin the device being held in a shut or closed position. In thissituation, the second pressure-actuated bellows device is actuated bythe first pressure-actuated bellows device only.

To introduce a fluid into the fluid-tight space defined by the outerstructure, the closed end of the outer structure and the support means,a through hole may be provided in the outer structure, to which hole,for example, a non-return valve may be connected.

Subsequently, the device may, for example, be connected to a gas liftvalve, and then lowered into the well so as to then be arranged in aproduction tubing.

When the device and the attached gas lift valve are arranged in theproduction tubing, the second pressure-actuated bellows device, which isarranged in the space defined by the support means, the outer structureand the open end of the outer structure, will be subjected to anexternal force (in addition to the force from the firstpressure-actuated bellows device), for example, from a pressure of afluid in the well annulus. If the pressure in the fluid that is in thewell annulus is less than the preset pressure by which the firstpressure-actuated bellows device is actuated of the device will remainin its shut or closed position. By pressurizing a fluid and adding it tothe fluid that is in the well annulus, the pressure in the well annuluscan be increased until this pressure is as great as the pressure in thefluid-tight space. The pressure to which the first and the secondpressure-actuated device are subjected will then be equalized, whichwill result in the second pressure-actuated bellows device beingcompressed slightly (and the first pressure-actuated bellows devicebeing extended as a result), whereby this compression will cause thevalve body to be lifted out of engagement with the valve seat. Thedevice is now in its working position, and the surrounding fluid (thefluid in the annulus) is then allowed to flow through the device andinto the gas lift valve, whereby this also is actuated to be opened. Thefluid that is in the well annulus can now, via the device and the gaslift valve, flow from the annulus and into the production tubing, sothat, for example, completion fluid is displaced from the annulus.

The transmission of the axial movement between the first and the secondpressure-actuated bellows device may, however, also take place in otherways than by the first pressure-actuated bellows device being subjectedto a fluid pressure, for example, by mechanical transmission. A personskilled in the art will know how this may be done.

It is also conceivable that the first and the second pressure-actuatedbellows device can be filled with a fluid such that they have the samepressure, or that the pressure in the two pressure-actuated bellowsdevices may be different. This will give a better possibility ofcontrolling the range of movement of the pressure-actuated bellowsdevices.

In a preferred embodiment of the present invention, the first and/or thesecond pressure-actuated bellows device may be configured so as to becapable of being filled with or emptied of the fluid it contains,thereby allowing the pressure and/or the fluid it contains to bevaried/replaced.

In the volume defined by the bore in the outer housing and thepressure-actuated bellows device itself, one of the solutions accordingto the present invention may be that around each pressure-actuatedbellows device there is provided a nitrogen package (or another gas)that is pressurised, where the nitrogen package forms a bias that mustbe overcome if the pressure-actuated devices is to capable of beingactuated. The nitrogen package may be configured as a hollow, closedcylinder that is arranged around the pressure-actuated bellows device,or it may consist of several individual packages that are distributedaround the outer periphery of the pressure-actuated bellows device.Alternatively, the nitrogen package can be replaced by, for instance,disc springs or similar resilient devices. The nitrogen packages or theresilient devices for each of the pressure-actuated bellows elements mayhave the same or different resilience (modulus of elasticity).

The second pressure-actuated bellows device may be connected to a pistonrod or the like, which piston rod is further connected directly orindirectly to a valve body. Upon reciprocal actuation of the first andthe second pressure-actuated bellows device, the valve body will belifted out of or brought into contact with a valve seat, thereby openingor closing the device for through flow of a fluid.

If the second pressure-actuated bellows device is connected directly tothe valve body via a piston rod, there will be a direct lineartransmission of the movement of the second pressure-actuated bellowsdevice to the valve body. In one embodiment of the invention, the devicemay comprise two valve seats, between which the valve body is disposed,so that the device can be held closed when there is “equilibrium”between the two pressure-actuated bellows devices, or that the device isheld closed in that the external pressure (which surrounds the secondpressure-actuated bellows device) is greater than the preset pressurethat surrounds the first pressure-actuated bellows device.

It is also conceivable that the second pressure-actuated bellows deviceis connected via a piston rod to two sub-pistons, which two sub-pistonsare connected to each other through a hinge device. In one embodiment,the hinge device comprises a rotational axis, where the linear movementof the second pressure-actuated bellows device through the rotationalaxis is transmitted to the two sub-pistons. The rotational axis of thehinge device, in one embodiment, may be substantially transverse to thelongitudinal axis of the device. In another embodiment, it may intersectthe longitudinal axis or be arranged eccentrically in the device. Arotational axis is also conceivable that is not transverse, but thatforms another angle to the longitudinal axis of the device. In oneembodiment, the hinge device may comprise a pivot pin arranged to rotateabout its own longitudinal axis, which thus forms the rotational axis ofthe hinge device. The pivot pin is arranged to rotate relative to theouter structure and further comprises two engaging portions on eitherside of the pivot pin, which engaging portions are in engagement with arecess in their respective sub-piston.

The first and the second sub-piston may have a form that allows it toslide in the outer structure without any hindrance to the movement ofthe sub-pistons. In one embodiment, one sub-piston, in a portion at oneend thereof facing away from the other sub-piston, may be so configuredthat it fills the whole of the inner cross-section of the bore in theouter structure, whilst at the opposite end facing the second sub-pistonit may be configured so as to fill only a part of the cross-section ofthe bore. This allows the second sub-piston to fill a part of the sameinner cross-section. The second sub-piston, in one embodiment, may beconnected to a valve body by a connecting rod or piston, so that thevalve body may be arranged at a distance from the portion of the secondsub-piston that substantially fills the whole of the inner cross-sectionof the bore in the outer structure. The sub-pistons fill the innercross-section of the outer structure, but there is nonetheless fluidcommunication across the sub-pistons. This can also be obtained byconfiguring the sub-pistons with recesses in the surfaces on top of thesub-pistons and/or in an interior surface of the outer structure.

In an alternative embodiment of the present invention, the secondpressure-actuated bellows device, via a piston rod, is directlyconnected to an inner movable body in, for example, a gas lift valve,whereby the piston rod, when actuated by the second pressure-actuatedbellows device, will displace the inner movable body in the axialdirection of the gas lift valve, thereby opening the gas lift valve.

The device according to the present invention may also comprise lockingand sensor means, which locking means will be able to lock the device ina desired position (open or closed). The device will remain in thelocked position until the locking means is actuated to be opened, thistaking place, for instance, after the sensor means has measured acertain surrounding pressure. The locking means may, for example, beelectric, electromagnetic, etc.

Other advantages and characteristic features of the present inventionwill be clearly apparent from the following detailed description, theappended figures and the following claims.

The invention will now be described in more detail with reference to thefollowing figures, wherein:

FIG. 1 shows a first embodiment of a device according to the presentinvention;

FIG. 2 shows an embodiment of the device in FIG. 1 connected to a valve;

FIG. 3 shows a second embodiment of the device in FIG. 1; and

FIG. 4 shows a support means according to the present invention.

The figures show different embodiments of the device according to thepresent invention, where the device connected to other equipment is, forexample, intended to be arranged in a production tubing in an oil and/orgas well. One of skill in the art will appreciate how this is done andit is therefore not described in the description.

FIG. 1 shows a device according to the present invention. The devicecomprises an outer structure 1, which outer structure 1 in theillustrated embodiment is made in a single piece. However, it is alsoconceivable that the outer structure 1 is composed of a plurality ofelements that are put together so as to form the outer structure 1. Theouter structure 1 is configured having an internal bore 2, said bore 2being delimited by an end face E that is arranged at one end of theouter structure 1. Through this configuration, the outer structure 1will be closed at one end thereof and open at its opposite end.Connecting means are provided at the open end of the outer structure 1to enable the device to be connected to other equipment or tools, forexample, a gas lift valve 16 (only indicated). In the vicinity of theopen end of the outer structure 1, one or more through holes 15 areprovided, which holes 15 allow a surrounding fluid to flow into theouter structure 1.

In the outer structure 1 there is further provided a first and a secondpressure-actuated bellows device 3, 4.

The first and the second pressure-actuated bellows device 3, 4 areconfigured as a bellows in the form of an “accordion”, where a pluralityof sections or lamellae 6 are assembled to form the actual bellows. Thismay be done, for example, by welding, adhesive bonding or in some othersuitable way connecting the sections or lamellae 6 to each other.

The two pressure-actuated bellows devices 3, 4 are interconnected via asupport means 5. The outer section 6 (i.e., the end section) at one endof the pressure-actuated bellows devices 3, 4 is thus welded, adhesivelybonded or in some other manner connected to its respective side of thesupport means 5. The support means 5 is in turn fixedly mounted to theinside of the bore 2. This may be done, for example, by welding,adhesive bonding, screwing or some other suitable manner.

The second pressure-actuated bellows device 4, like the firstpressure-actuated bellows device 3, is at its other end (i.e., the endopposite the connection to the support means 5) connected to a flange 9.The flange 9 is further configured with a hole internally and with atleast one through hole 10 at one of its ends, which allows the secondpressure-actuated bellows device 4 to be connected via the flange to apiston rod 12. The piston rod 12 is then fastened to the flange 9 bymeans of a cotter pin, screw etc. (not shown) through the hole 10.

As the support means 5 is fixedly mounted on the inside of the bore 2,the support means 5 will form a fluid tight partition internally in theouter structure between the first and the second pressure-actuatedbellows device 3, 4. This means that a closed space 11 is formed, whichclosed space 11 encircles the first pressure-actuated bellows device 3.This closed space 11 is filled with a fluid, for example, nitrogen underpressure, which means that the first pressure-actuated bellows issubjected to a desired “bias”. This bias will, depending upon its size,actuate the first pressure-actuated bellows device 3, so that it iscompressed. The closed space 11 is filled in that in the outer structurethere is provided a through hole (not shown), to which, for example, anon-return valve is connected.

However, it is also conceivable that the first pressure-actuated bellowsdevice 3 can be actuated by an actuating mechanism (not shown), therebymaking it unnecessary to preset the closed space 11 at a pressure. Theactuating mechanism may then be so configured that it transmits orapplies a force to the first pressure-actuated device 3 such that it iscompressed or extended in its axial direction. The actuating mechanismmay, for example, be so configured that it is activated electrically,hydraulically etc.

Similarly, a space will also be formed around the secondpressure-actuated bellows device 4, which space is defined by thesupport means 5, the outer structure 1 and the open end of the outerstructure. The second pressure-actuated bellows device 4 will then alsobe subjected to an external force, for example, from a pressure in afluid in the well annulus.

Each of the pressure-actuated bellows devices 3, 4 is made hollow andholds an incompressible fluid, and the bellow devices 3, 4 must thus beconfigured as a closed unit. This can be done in different ways, forexample, in that one end of the pressure-actuated devices 3, 4 isconnected to the support means 5, whilst the opposite end is delimitedby the flange 7, 9.

The support means 5 according to FIG. 1 is configured as a closedcylinder, where a hole (not shown) is provided through the material ofthe top face and the bottom face of the closed cylinder. The open end(i.e., the end opposite the flange 7, 9) of the first and the secondpressure-actuated bellows device 3, 4 is then connected to this throughhole so that a closed unit is formed, consisting of the firstpressure-actuated bellows device 3, the intermediate support means 5 andthe second pressure-actuated bellows device 4.

Internally in the support means 5 there is further provided a movablepiston 101 (see also FIG. 4), this piston being allowed to be moved inthe axial direction of the support means 5. The piston can further beconfigured such that, together with the through hole in the top and/orbottom face of the support means 5, it forms a metal-to-metal seal,which means that when the piston is brought into contact with the top orbottom face of the support means, the first or the secondpressure-actuated bellows device 3, 4 will not be allowed a furthermovement in its axial direction.

A sleeve 104 may further be provided internally in the support means 5,which sleeve will extend some distance inwards in the closed space ofthe first and/or the second pressure-actuated bellows device 3, 4. Thiswill allow the first and/or the second pressure-actuated bellows device3, 4 to be extended or compressed until the pressure-actuated bellowsdevice 3, 4 is brought into contact with the sleeve 104, whereby furtherextension or compression of the pressure-actuated bellows device 3, 4 isstopped.

In the support means 5 there may also be provided a delay device 102,the purpose of said delay device 102 being to delay the flow of theincompressible fluid into the support 5. In its simplest form, the delaydevice 102 comprises a plate formed having one or more through holes103. The delay means 102 is supported in a suitable way in the supportmeans 5.

FIG. 1 shows a first embodiment of the device according to theinvention, where the second pressure-actuated bellows device 4 isconnected to the piston rod 12. This is done in that the flange 9, whichis connected to the second pressure-actuated bellows device 4, isdesigned to receive the piston rod 12, said flange 9 and piston rod 12being connected via a suitable connection. The flange 9 is thusconfigured with a through hole 10, where by means of a bolt, screw,cotter pin or the like the piston rod 12 may be secured to the flange 9.The piston rod 12 is further so configured that it can be brought intocontact with a body, for example, with a movable inner body in a gaslift valve 16 (only indicated), whereby the piston rod 12 upon actuation(extension or compression) of the second pressure-actuated bellowsdevice 4 will then move the inner movable body in the axial direction ofthe gas lift valve, so that the gas lift valve is opened or closed. Thedevice is, moreover, configured with one or more through holes 15 in theouter structure 1, which through holes 15 are placed in the area aroundthe second pressure-actuated bellows device 4.

A second embodiment of the device according to the present invention isshown in FIG. 2, where the piston rod 12 is connected to the secondpressure-actuated bellows device 4 in the same way as explained above.In this embodiment, however, the piston rod 12 is not connected directlyto the inner movable body in the gas lift valve 16. The piston rod 12,at the end thereof opposite the connection to the flange 9, is in thiscase connected to a valve body 13, which valve body 13 is disposedbetween two valve seats 14. When the device is preset at a pressure inthe space 11, this pressure will actuate the first pressure-actuatedbellows device 3 so that it is compressed. This results in thecompression of the first pressure-actuated bellows device 3, via thesupport means 5, being transmitted to the second pressure-actuatedbellows device 4, whereby it is extended a certain length in its axialdirection. As the second pressure-actuated bellows device 4 is connectedto the piston rod 12 and the piston rod 12 is further connected to avalve body 13, the valve body 13 will be pushed into contact with thelower valve seat 14, when seen in the figure. The device is then closedand will be lowered into the well for assembly with a gas lift valve 16(only indicated). When the device and the gas lift valve 16 are arrangedin the production tubing (not shown), the surrounding fluid in the wellannulus will flow in through the opening(s) 15 in the outer structure 1,and the second pressure-actuated bellows device will then be subjectedto a force. If the preset pressure, which is in the space 11, is greaterthan the pressure in the annulus, a pressure will be applied in theannulus, so that the pressure therein increases. When the presetpressure and the pressure in the annulus are equal, the secondpressure-actuated bellows device 4 will then have been actuated to becompressed, thereby achieving a “balanced” state between the first andthe second pressure-actuated bellows device 3, 4. The valve body 13 willthen have been brought out of engagement with the lower valve seat 14,whereby the surrounding fluid from the annulus is allowed to flowthrough the valve seat 14. The fluid will then flow into the gas liftvalve 16 and the inner movable body therein will then be actuated sothat the gas lift valve is opened. The surrounding fluid will then beable to flow from the annulus and through the device and the connectedgas lift valve 16 and into the production tubing. In the case where thesurrounding fluid has a greater pressure than the preset pressure in thespace 11, the second pressure-actuated bellows device 4 will becompressed so that the valve body 13 is displaced in the axial directionof the device, whereby the valve body 13 is brought into engagement withthe upper valve seat 14, when seen in the figure. Then the device willalso be in a closed position. This means that the device according tothe present invention will only open within a small, predefined range(i.e., in the range around the position of equilibrium of the twopressure-actuated bellows devices 3, 4.)

FIG. 3 shows a further embodiment of the device according to the presentinvention, where it is seen that the piston rod 12 is now connected to afirst sub-piston 17, which sub-piston 17, via a hinge device 18, isfurther connected to a second sub-piston 19. The second sub-piston 19 ismoreover connected to a piston rod 12, which in turn is connected to avalve body 13. The valve body 13 is, as in the second embodiment,disposed between two valve seats 14.

The first sub-piston 17 comprises a first end portion 27, whichcomprises the contact face 28. This first end portion 27 is shown sothat a cross-section of this end portion 27 fills almost the whole bore2 of the outer structure 1. Furthermore, the first sub-piston 17comprises a second end portion 29 which faces away from the first endportion 27, which second end portion 29 fills only a part of the bore 2of the outer structure 1. This second end portion 29 is also connectedto a hinge device 18 comprising a pivot pin 30 and a first engagingportion 31 which rests in a recess 32 in the second end portion 29 ofthe first sub-piston 17. The hinge device 18 further comprises a secondengaging portion 33 which extends from the pivot pin 30 on the oppositeside relative to the first engaging portion 32. This second engagingportion 33 rests in a recess 34 in a second end portion 38 of a secondsub-piston 19. The motion of the first sub-piston 17 is transmitted tothe second sub-piston 19 through the hinge device 18, whereby the secondsub-piston 19 will be moved in the opposite direction to the movement ofthe first sub-piston 17. The movement takes place essentially in anaxial direction of the device. The second end portion 38 of the secondsub-piston 19 also has a smaller cross-sectional extent than the bore 2in the outer structure 1, so that there is room for the hinge device 18and the movement of the sub-pistons 17, 19. A first end portion 39 ofthe second sub-piston 19, which faces way from the first sub-piston 17,covers essentially the whole cross-section of the bore 2 in the outerstructure 1. To the end of this first end portion 39 there is connecteda piston rod 12 to which the valve body 13 is secured. A movement of thesecond sub-piston 19 will thus move the valve body 13 relative to thevalve seat 14. The device according to this embodiment will be closed oropened in the same way as described above.

Only elements relating to the invention have been explained anddescribed above and a person of skill in the art will appreciate thatthe outer structure can be formed as one unit or it may comprise severalelements that are joined together. The valve device should further havesuitable means for connection or installation in a process fluid stream.The skilled person will further understand that a number of embodimentsand modifications of the described and illustrated embodiment can beprovided within the scope of the invention as defined in the followingclaims.

1. A device, in particular for use in an offshore or onshore oil and/orgas well, comprising an outer structure provided with a bore and apressure-actuated bellows arranged therein, characterised in that thepressure-actuated bellows is formed of a first and a secondpressure-actuated bellows device, which first and secondpressure-actuated bellows device, via a support means, are in fluidcommunication with each other, said support means being fixedly mountedinternally in the outer structure, so that the support means delimits anopen and a closed space for respectively the first and the secondpressure-actuated bellows device in the outer structure, which closedspace comprises means for pressurizing the closed space, whilst the openspace is designed to be in fluid communication with a surrounding fluid.2. A device according to claim 1, characterised in that in the outerstructure a bore is provided.
 3. A device according to claim 1,characterized in that the support means is fixedly mounted internally inthe bore.
 4. A device according to claim 1 or 3, characterised in thatthe support means forms a closed cylinder, the top and bottom face ofthe cylinder, via through holes, being connected to the first and thesecond pressure-actuated bellows device.
 5. A device according to claim3, characterised in that internally in the support means at least onepiston is provided.
 6. A device according to claim 3, characterised inthat a delay device is provided in connection with the support means. 7.A device according to claim 6, characterised in that the delay device isa plate comprising at least one through hole.
 8. A device according toclaim 1, characterised in that at least one stop face internally in thesupport means delimits the axial movement of the first and the secondpressure-actuated bellows device.
 9. A device according to claim 1,characterised in that the first and the second pressure-actuated bellowsdevice are made of a metallic, elastomeric or non-metallic material. 10.A device according to claim 3, characterised in that the first and thesecond pressure-actuated bellows device and the support means are filledwith an incompressible fluid.
 11. A device according to claim 1,characterised in that a resilient element is arranged around the firstand/or second pressure-actuated bellows device.
 12. A device accordingto claim 11, characterised in that the resilient element is a nitrogenpackage, one or more springs or another biasing device.
 13. A deviceaccording to claim 1, characterised in that the first and the secondpressure-actuated bellows device in a lower stop position are configuredto have maximum compression.